... 3. Protection and halide exchange set the stage for homologation with allylmagnesium chloride. Ozonolysis followed by condensation with the acyl oxazolidinone 6 set the last two stereogenic centers ...

... ), each enantiomer of which is commercially available in bulk. After protection and ozonolysis, the first singly-aminated stereogenic center was installed by enantioselective, and therefore diastereoselective ...